How to measure dielectric constant using a microstrip line?

Hello Forum,

How do I measure the dielectric constant of a substrate using a microstrip line? Someone said that I could layout a microstrip line on a the substrate backed by a ground plane and use that fixture to do the measurement. Any help on how to do it?

Thanks,

P.

You would typically use a resonator such as a microstrip ring.

http://www.microwaves101.com/encyclo...dielectric.cfm

use TDR to measure velocity then derive dielectric constant.

Er changes with F so a TDR will give poor results. A resonator is one of the more accurate ways to do it. You can build several resonators at different frequencies, an a notch in magnitude response is easy to measure at a precise frequency; no phase needed.